Try travelling along the coast of each island mashing L3 like mad (and stay as close to the coast line as possible since some blast shards are out in the water), then try going along each train line mashing L3 like mad. After that, not sure, since you claim you have the ones that aren't on the map normally.

I was on 349 for days on my good save, it drove me crazy wasting hours endlessly checking piers and areas I knew I'd checked before, naturally I'd gotten all the usual "problem" high up / far out shards, so I was at a loss as to where the one I must have missed was.

I eventually abandoned that save and was just up to around 300 on my evil save when I noticed a shard up a pole by the northwestern medical clinic in the Warren. Funny how I hadn't gotten that one previously I thought, so I scanned for it and found it didn't seem to pop up easily on the minimap - though obviously it is harder to see the shards on the minimap on the evil playthrough due to the colour of the sky - I recall it took some effort to get the blue dot to appear.

On a hunch I went back to my 349 save and battled my way up to that clinic and wouldn't you know it, that was my final shard, pop go my trophies. So I suggest going to the NW corner of the Warren and visually checking for the shard there, on the maps it's the blast shard touching the medical clinic.

Another tip I have generally is to turn the HUD faint, and turn the camera so the mini-map is displayed clear against the sky - the blue dots show up real easy that way, particularly on a good playthrough.

It is out there - good luck!

Edit: Jul 31, 11 6:29am

-------------------"In this world nothing is certain but death and taxes" - Benjamin Franklin 1789